46 lines
1.9 KiB
Markdown
46 lines
1.9 KiB
Markdown
# JScript
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**NOTE: This had nothing to do with Microsoft's dialect of EcmaScript**
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**WARNING: Currently, this code is mostly undocumented. Proceed with caution and a psychiatrist.**
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JScript is an engine, capable of running EcmaScript 5, written entirely in Java. This engine has been developed with the goal of being easy to integrate with your preexisting codebase, **THE GOAL OF THIS ENGINE IS NOT PERFORMANCE**. My crude experiments show that this engine is 50x-100x slower than V8, which, although bad, is acceptable for most simple scripting purposes. Note that although the codebase has a Main class, this isn't meant to be a standalone program, but instead a library for running JavaScript code.
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## Example
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The following will create a REPL using the engine as a backend. Not that this won't properly log errors. I recommend checking out the implementation in `Main.main`:
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```java
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var engine = new Engine(true /* false if you dont want debugging */);
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var env = new Environment(null, null, null);
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var debugger = new DebugServer();
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// Create one target for the engine and start debugging server
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debugger.targets.put("target", (socket, req) -> new SimpleDebugger(socket, engine));
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debugger.start(new InetSocketAddress("127.0.0.1", 9229), true);
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// Queue code to load internal libraries and start engine
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engine.pushMsg(false, null, new Internals().getApplier(env));
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engine.start();
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while (true) {
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try {
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var raw = Reading.read();
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if (raw == null) break;
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// Push a message to the engine with the raw REPL code
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var res = engine.pushMsg(
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false, new Context(engine).pushEnv(env),
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new Filename("jscript", "repl.js"), raw, null
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).await();
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Values.printValue(null, res);
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}
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catch (EngineException e) { Values.printError(e, ""); }
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catch (SyntaxException ex) {
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System.out.println("Syntax error:" + ex.msg);
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}
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catch (IOException e) { }
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}
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```
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